Method and apparatus for providing contention-based resource zones in a wireless network

ABSTRACT

A base station employs control signaling for contention-based uplink access from user equipment devices to the base station. Contention-based access configuration is performed via physical downlink control channel signaling. Configuration data sent to the user equipment devices identifies multiple contention-based access zones, along with minimum power headroom values for each contention-based access zone. A probability factor may be used to lower collision possibility by influencing whether the user equipment devices perform contention-based uplink access.

This application is related to co-owned U.S. patent application Ser. No.12/859,514, entitled METHOD AND APPARATUS FOR USING CONTENTION-BASEDRESOURCE ZONES FOR TRANSMITTING DATA IN A WIRELESS NETWORK and filedconcurrently herewith.

This application is related to co-owned U.S. patent application Ser. No.12/859,545, entitled METHOD AND APPARATUS FOR DETERMINING WHEN TO USECONTENTION-BASED ACCESS FOR TRANSMITTING DATA IN A WIRELESS NETWORK andfiled concurrently herewith

TECHNICAL FIELD

Embodiments of the subject matter described herein relate generally towireless communication systems. More particularly, embodiments of thesubject matter relate to techniques, procedures, and technologies thatsupport contention-based uplink access in a wireless communicationsystem.

BACKGROUND

Wireless communication systems are well known, and the operation ofwireless communication systems are usually governed by publishedspecifications, standards, and operating protocols. For example, LongTerm Evolution (LTE) refers to a recent standard for mobile networktechnology, and the current LTE specification is published by the 3rdGeneration Partnership Project (3GPP). LTE Advanced (LTE-A) is aproposed extension of LTE that is expected to be finalized in the year2011.

A wireless device in an LTE system (i.e., a user equipment or UE device)may experience undesirable amounts of latency associated with power-up,initialization, and/or connection to the wireless network.Contention-based uplink access has been proposed as a way to reduce suchlatency. Contention-based uplink access would allow multiple UE devicesto compete for uplink resources on a shared channel supported by thebase station, in addition to or in lieu of the traditional uplink accessscheme that utilizes dedicated and scheduled resources.

A successful deployment of contention-based uplink access will leveragecertain access mechanisms, communication protocols, and proceduresperformed by the UE devices and the base station. Accordingly, it isdesirable to have effective and reliable techniques and technologiesthat enable a wireless communication system to employ contention-baseduplink access from UE devices to base stations.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the subject matter may be derived byreferring to the detailed description and claims when considered inconjunction with the following figures, wherein like reference numbersrefer to similar elements throughout the figures.

FIG. 1 is a simplified diagram that illustrates an exemplary wirelesscommunication system;

FIG. 2 is a simplified diagram that illustrates a user equipment deviceand a base station;

FIG. 3 is a diagram that schematically depicts an exemplary allocationof physical resource blocks for a wireless communication system;

FIG. 4 is a diagram that illustrates exemplary data fields associatedwith contention-based configuration data;

FIG. 5 is a flow chart that illustrates an exemplary operating processperformed by a base station;

FIGS. 6-9 are flow charts that illustrate exemplary operating processesperformed by a user equipment device;

FIG. 10 is a flow chart that illustrates another exemplary operatingprocess performed by a base station; and

FIG. 11 is a diagram that illustrates timing associated with the uplinktransmission of a data packet and the downlink transmission of acorresponding acknowledgement message.

DETAILED DESCRIPTION

The following detailed description is merely illustrative in nature andis not intended to limit the embodiments of the subject matter or theapplication and uses of such embodiments. As used herein, the word“exemplary” means “serving as an example, instance, or illustration.”Any implementation described herein as exemplary is not necessarily tobe construed as preferred or advantageous over other implementations.Furthermore, there is no intention to be bound by any expressed orimplied theory presented in the preceding technical field, background,brief summary or the following detailed description.

Techniques and technologies may be described herein in terms offunctional and/or logical block components, and with reference tosymbolic representations of operations, processing tasks, and functionsthat may be performed by various computing components or devices. Suchoperations, tasks, and functions are sometimes referred to as beingcomputer-executed, computerized, software-implemented, orcomputer-implemented, and one or more processor devices can carry outthe described operations, tasks, and functions by manipulatingelectrical signals representing data bits at memory locations in thesystem memory, as well as other processing of signals. It should beappreciated that the various block components shown in the figures maybe realized by any number of hardware, software, and/or firmwarecomponents configured to perform the specified functions. For example,an embodiment of a system or a component may employ various integratedcircuit components, e.g., memory elements, digital signal processingelements, logic elements, look-up tables, or the like, which may carryout a variety of functions under the control of one or moremicroprocessors or other control devices.

The subject matter presented here relates to a wireless communicationsystem. More particularly, the subject matter relates to an orthogonalfrequency division multiplexing (OFDM) based system having one or morebase stations, each servicing one or more wireless devices. Theparticular system embodiment described here represents a wirelesscommunication system that operates (at least in part) in accordance withthe LTE specification. Moreover, the system embodiment described here isintended for operation (at least in part) in accordance with theproposed LTE-A specification. It should be appreciated that the subjectmatter is not limited or otherwise restricted to an LTE or an LTE-Adeployment, and that the techniques, methodologies, procedures, andprotocols described here could be extended for use in other systemconfigurations. As one of ordinary skill in the art will recognize, avariety of LTE specifications are available from the 3GPP.

FIG. 1 is a simplified diagram that illustrates an exemplary wirelesscommunication system 100. For this example, the system 100 is an OFDMbased LTE system. In this regard, many of the fundamental and basicoperating features, characteristics, and functions of the system 100 arecompatible with the published LTE specifications. Accordingly,conventional and well known aspects of the system 100 will not bedescribed in detail here. The simplified embodiment of the system 100includes a base station that communicates with three wireless devices.For consistency with LTE terminology, the base station will be referredto herein as an evolved NodeB, eNodeB, or eNB, and a wireless devicewill be referred to herein as a user equipment device, a UE device, orsimply a UE. Thus, FIG. 1 shows one eNB 102 and three UE devices 104 inthe system 100. It should be appreciated that a practical deployment ofthe system 100 could include any number of eNBs 102 (depending on thedesired wireless coverage area), and that each eNB 102 could supportmore or less than three UE devices 104.

FIG. 2 is a simplified diagram that illustrates one UE device 104 andthe eNB 102, along with several data communication channels (uplink fromthe UE device 104 to the eNB 102, and downlink from the eNB 102 to theUE device 104) established between them. The UE device 104 generallyincludes, without limitation: a wireless communication module 202; aprocessor module 204; and a suitable amount of memory 206. Theseelements of the UE device 104 are operatively coupled together using anappropriate interconnection architecture or arrangement, as is wellunderstood. The eNB 102 generally includes, without limitation: awireless communication module 208; a controller 210; and a suitableamount of memory 212. These elements of the eNB 102 are operativelycoupled together using an appropriate interconnection architecture orarrangement, as is well understood. In practice, the UE device 104 andthe eNB 102 will include additional components, functionality, logic,and elements that are suitably configured to perform conventionaloperations and procedures that are unrelated to the particular subjectmatter described here. For the sake of brevity and clarity, suchconventional items will not be described in detail here.

The wireless communication module 202 may be implemented as atransceiver and one or more antennas. In certain embodiments, thewireless communication module 202 utilizes a plurality of antennas thatcooperate to support Multiple Input Multiple Output (MIMO)communication. The wireless communication module 202 can send uplinkmessages and uplink control signaling information to the eNB 102, whilereceiving downlink messages and downlink control signaling informationfrom the eNB 102. For this embodiment, the wireless communication module202 can transmit data packets using the LTE frame structure. In LTE,each radio frame consists of ten subframes, and each subframe is onemillisecond long. Each subframe is comprised of control and dataportions. In the downlink, the control part consists of informationregarding the size of the control part in number of OFDM symbols,acknowledgements pertaining to past uplink data transmissions,uplink/downlink grants, and power control fields. The data part consistsof data packets to one or more UEs. In the uplink, the control partconsists of information regarding channel state information, schedulingrequest indication, and acknowledgements pertaining to past downlinkdata transmissions. The data part consists of data packets to one ormore UEs.

For this particular embodiment, the wireless communication module 202supports the following wireless channels: a physical uplink sharedchannel (PUSCH) 214; a physical uplink control channel (PUCCH) 216; aphysical broadcast channel (PBCH) 218; a physical downlink sharedchannel (PDSCH) 220; and a physical downlink control channel (PDCCH)222. The PUSCH 214 can be shared by a plurality of UE devices in thesystem 100 for purposes of data transmission. Moreover, uplink accessvia the PUSCH 214 may be contention-based and/or scheduled (as describedin more detail below). The PUCCH 216 carries uplink control information(e.g., uplink scheduling requests, ACK/NACK information, and channelquality information). In this regard, the PUCCH 216 is considered to bea signaling channel between the UE device 104 and the eNB 102. The PBCH218 carries cell-specific control information from the eNB 102 to the UEdevices within range of the transmitting eNB 102. The PDSCH 220 isutilized for data and multimedia transport from the eNB 102 to the UEdevice 104. The PDCCH 222 conveys control information for the UEdevices. In this regard, the PDCCH 222 is considered to be a signalingchannel between the eNB 102 and the UE device 104.

The processor module 204 is operatively associated with the wirelesscommunication module 202, and it can process and analyze information anddata received by the wireless communication module 202, and process andprepare information for transmission by the wireless communicationmodule 202. The processor module 204 may include or be implemented witha general purpose processor, a content addressable memory, a digitalsignal processor, an application specific integrated circuit, a fieldprogrammable gate array, any suitable programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination designed to perform the functions described here. Aprocessor device utilized by the processor module 204 may be realized asa microprocessor, a controller, a microcontroller, or a state machine.Moreover, a processor device may be implemented as a combination ofcomputing devices, e.g., a combination of a digital signal processor anda microprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a digital signal processor core, orany other such configuration. In practice, the processor module 204 mayinclude one processor device or a plurality of cooperating processordevices.

The memory 206 may be realized as RAM memory, flash memory, EPROMmemory, EEPROM memory, registers, a hard disk, a removable disk, or anyother form of storage medium known in the art. In this regard, thememory 206 can be coupled to the processor module 204 such that theprocessor module 204 can read information from, and write informationto, the memory 206. In the alternative, the memory 206 may be integralto the processor module 204. As an example, the processor module 204 andthe memory 206 may reside in an ASIC. In practice, a functional orlogical component of the UE device 104 and/or one or more applicationsexecuted by the UE device 104 might be realized using program code thatis maintained in the memory 206. Moreover, the memory 206 can be used tostore data utilized to support the operation of the UE device 104,including, without limitation, contention-based configuration data, anidentifier of the UE device 104, buffered data to be transmitted by thewireless communication module 202, and the like (as will become apparentfrom the following description).

For the eNB 102, the wireless communication module 208 may beimplemented as a transceiver and one or more antennas. In certainembodiments, the wireless communication module 208 utilizes a pluralityof cooperating antennas that support MIMO communication. The wirelesscommunication module 208 can send downlink messages and downlink controlsignaling information to the UE device 104, while receiving uplinkmessages and uplink control signaling information from the UE device104. For this embodiment, the wireless communication module 208 cantransmit data packets using the LTE frame structure. Notably, thewireless communication module 208 also supports the various channelsdescribed above with reference to the wireless communication module 202,namely, the PUSCH 214, the PUCCH 216, the PBCH 218, the PDSCH 220, andthe PDCCH 222.

The controller 210 is operatively associated with the wirelesscommunication module 208, and it can process and analyze information anddata received by the wireless communication module 208, and process andprepare information for transmission by the wireless communicationmodule 208. The controller 210 may include or be implemented with ageneral purpose processor, a content addressable memory, a digitalsignal processor, an application specific integrated circuit, a fieldprogrammable gate array, any suitable programmable logic device,discrete gate or transistor logic, discrete hardware components, or anycombination designed to perform the functions described here. Aprocessor device utilized by the controller 210 may be realized as amicroprocessor, a controller, a microcontroller, or a state machine.Moreover, a processor device may be implemented as a combination ofcomputing devices, e.g., a combination of a digital signal processor anda microprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a digital signal processor core, orany other such configuration. In practice, the controller 210 mayinclude one processor device or a plurality of cooperating processordevices.

The memory 212 may be realized in the manner described above for thememory 206 of the UE device 104. Moreover, a functional or logicalcomponent of the eNB 102 and/or one or more applications executed by theeNB 102 might be realized using program code that is maintained in thememory 212. Moreover, the memory 212 can be used to store data utilizedto support the operation of the eNB 102, including, without limitation,contention-based configuration data, resource allocation information,and the like (as will become apparent from the following description).

Power-up latency and network connection latency experienced by UEdevices in a wireless network can be annoying and frustrating to users.In an LTE based system, some of this latency can be attributed to themanner in which physical resources are dedicated to UE devices in a timescheduled manner. In contrast, the system 100 described here utilizescontention-based uplink access as a way to reduce latency experienced bythe UE devices 104. Such latency reduction is achieved because a UEdevice 104 need not transmit a scheduling request indicator (SRI) andwait for an uplink grant issued by the eNB 102 before sending its data.Rather, when using contention-based uplink access, the UE devices 104are allowed to transmit data on a designated and reserved PUSCH region,and an identifier (such as the cell radio network temporary identifieror C-RNTI) is added to the uplink message to identify the transmittingUE device. This methodology is most beneficial under low system loadconditions where most resource blocks are not being used. Thecontention-based uplink access methodology can also be used formachine-type communication (i.e., machine to machine communication) topossibly lower overhead associated with uplink data transmission. Tosupport such contention-based access, standardized mechanisms andprocedures should be defined and implemented. In this regard, thefollowing description addresses certain control signaling forcontention-based access and presents a preliminary UE procedure forcontention-based access.

FIG. 3 is a diagram that schematically depicts an exemplary allocationof physical resource blocks for the system 100. In this example, threecontention-based resource zones 302, 304, 306 are defined. In practice,however, any number of contention-based resource zones could beutilized. Notably, any UE device serviced by an eNB is able to use thecontention-based resource zones 302, 304, 306 because, by definition,those zones are associated with shared (not dedicated) resources. FIG. 3also depicts an area 308 corresponding to assigned or dedicatedresources that are utilized for traditional schedule based uplinkaccess. As described in more detail below, certain situations might callfor scheduled uplink access using dedicated physical resources ratherthan contention-based access. Moreover, contention-based uplink accesscan be used for an initial amount of data to be transmitted by a UEdevice, and additional data can follow using scheduled uplinktransmission. Accordingly, the area 308 of assigned or dedicatedresources may be utilized in a conventional manner for purposes ofscheduled uplink access.

FIG. 3 also schematically depicts the available demodulation referencesignal (DMRS) 320 that are available for use by the UE devices duringcontention-based uplink transmissions. In this context, a DMRS andassociated cyclic shift represents a pilot signal used by thetransmitting UE device, as is well understood by one of ordinary skillin the art. In certain embodiments, a UE device randomly selects a DMRScyclic shift when transmitting on a contention-based access zone. Thisfeature provides support for spatial separation and increases thelikelihood that the eNB will successfully decode uplink accesstransmissions from more than one UE device when collisions do occur.This also allows the eNB to detect collisions even if the PUSCH cannotbe decoded because the eNB can detect that different DMRS cyclic shiftsare being transmitted on the contention-based zone using energydetection. Thus, although the eNB cannot decode the data packets due tocollision, it can detect the collision itself.

The contention-based resource zones 302, 304, 306 are used for the PUSCH214 (see FIG. 2), i.e., they are used for uplink access to the eNB 102.Each of the contention-based resource zones 302, 304, 306 includes arespective number of physical resource blocks (PRBs). For purposes ofthis description, a PRB in a contention-based resource zone is definedas a group of subcarriers by a number of OFDM symbols. (For example, fora normal cyclic prefix subframe in LTE, a PRB is 12 subcarriers infrequency and 14 OFDM symbols in time.)

Notably, each of the contention-based resource zones 302, 304, 306 has arespective modulation and coding scheme (MCS) assigned thereto; incertain implementations, each contention-based resource zone has adifferent MCS assigned thereto. For example, and without limitation, thezone 302 may be assigned an MCS corresponding to QPSK and R=1/3 (where Rrepresents coding rate), the zone 304 may be assigned an MCScorresponding to QPSK and R=3/4, and the zone 306 may be assigned an MCScorresponding to 16-QAM and R=3/4. It should be appreciated thatdifferent modulation and/or coding techniques could be utilized in anembodiment of the system 100, and that these examples are not exhaustiveor required.

For this particular embodiment, UE devices are allowed to transmit inone of the contention-based resource zones 302, 304, 306 using thepredefined MCS and Transport Block Size (TBS) assignment given in thegrant (in this context, TBS refers to the amount of data in bits thatthe UE can transmit in a particular zone). This particular grantprovides information about the contention-based resource zones i.e., thePDCCH-based configuration described below). A minimum power headroomrestriction may be implemented so that a UE device is not allowed totransmit in a particular zone if the assigned MCS cannot be supported bythat UE device (e.g., UE devices at the cell edge are not allowed totransmit in 16-QAM zones). In this case, the grant is common to all UEsand it provides information about MCS, TBS, power headroom, and possiblyother parameters that UEs using contention-based access can read.

Contention-based access parameters of the UE devices can be configuredsemi-statically via radio resource control (RRC) signaling, dynamicallyor in a semi-persistent manner via PDCCH assignment. RRC signalingincurs the least amount of overhead, however the process is slow and,because RRC signaling is common, all UE devices will be required to readand update the RRC signaling information in their internal databases.Although the timing of RRC signaling may vary from one network toanother, RRC information is typically sent once every forty subframes(i.e., much less frequently than PDCCH signaling information). Dynamicconfiguration of contention-based access parameters can be performed viaPDCCH signaling. This allows the configuration data to be changed everysubframe, which may incur high PDCCH overhead. If contention-basedaccess is only used when system load is low, then PDCCH overhead may notbe an issue. However, the provision of contention-based configurationdata can also be performed in a semi-persistent manner to save PDCCHoverhead if needed. (Semi-persistent is defined herein to mean that theconfiguration is provided once and remains valid for a certain amount oftime or until canceled.) Such a methodology allows contention-basedaccess to be supported for other purposes, for example machine-typecommunication.

To accommodate PDCCH configuration of contention-based access, a newdownlink control information (DCI) format is defined. This new DCIformat may be considered to be a contention-based access uplink grant,and it may be based on the existing uplink grant structure defined inthe LTE specification. In this regard, FIG. 4 is a diagram thatillustrates exemplary data fields associated with contention-basedconfiguration data 400. The configuration data 400 can be sent from theeNB 102 to the UE devices 104 in an appropriate signaling channel, e.g.,the PDCCH, and in an appropriate format. Thus, the configuration data400 could be updated in a dynamic manner, once every subframe. Incertain embodiments, the configuration data 400 is sent using RRC.

Although the content of the contention-based configuration data 400 mayvary from one embodiment to another, the configuration data 400 for thisexample includes: a hopping flag 402; physical resource block assignmentdata 404; MCS data 406; zone data 408 associated with thecontention-based resource zones; and minimum power headroom data 410.The hopping flag 402 is used to provide frequency diversity, as calledfor in the LTE specification, 3GPP TS 36.213 V9.2.0 (2010-06), Section8.4. The physical resource block assignment data 404 identifies the PRBsassigned to each contention-based resource block. In practice,therefore, a given PRB can be assigned to only one contention-basedresource block at any given time. As explained above, multiplecontention-based resource zones may be configured. This allows differentzones to be defined to lower collision probability. Moreover, differentzones can be used to support different MCSs, data packet sizes, or datarates. Accordingly, the MCS data 406 is utilized to identify theparticular MCSs that are assigned to each contention-based resourcezone. The zone data 408 identifies the plurality of differentcontention-based resource zones in an appropriate manner. For example,the zone data 408 may indicate the number of contention-based resourcezones available to the UE devices, the size of each contention-basedresource zone, etc. In practice, the zone data 408 and the physicalresource block assignment data 404 could be merged together into asingle field.

The minimum power headroom data 410 identifies a respective minimumpower headroom value for each of the contention-based resource zones.The minimum power headroom value that is obtained or defined for eachcontention-based access zone can be considered by the UE devices whendetermining which contention-based access zone (if any) to use foruplink access. This ensures that a transmitting UE device meets thestated minimum power requirement before it can transmit in acontention-based access zone. Thus, the UE device will not waste poweron an uplink transmission that cannot be decoded at the eNB due toinadequate transmission power. The manner in which the UE devicesprocess the minimum power headroom values is described in more detailbelow.

As mentioned previously, the eNB sends the contention-basedconfiguration data 400 to the UE devices. In this regard, FIG. 5 is aflow chart that illustrates an exemplary operating process 500 performedby a base station (e.g., an eNB). The process 500 relates to theprovision of the contention-based configuration data to the UE devicessupported by that particular eNB. The various tasks performed inconnection with a process described herein (such as the process 500) maybe performed by software, hardware, firmware, or any combinationthereof. For illustrative purposes, a described process may refer toelements mentioned above in connection with FIGS. 1-4. In practice,portions of a described process may be performed by different elementsof the described system, e.g., a base station, a UE device, a networkinfrastructure device, or the like. It should be appreciated that adescribed process may include any number of additional or alternativetasks, the tasks shown in a figure need not be performed in theillustrated order, and a described process may be incorporated into amore comprehensive procedure or process having additional functionalitynot described in detail herein. Moreover, one or more of the tasks shownin a figure could be omitted from an embodiment of the depicted processas long as the intended overall functionality remains intact.

For this particular implementation, the process 500 is performed by aneNB. The process 500 may begin with the eNB determining a plurality ofcontention-based resource zones to be used for the PUSCH of that eNB(task 502). In practice, the number of contention-based resource zonesand the PRBs assigned to each contention-based resource zone may bedetermined in response to system load, expected data packet sizes (e.g.,TCP/IP acknowledgement, voice-over-IP packet), number of machine-typeusers, past collisions, etc.). The process 500 also assigns a modulationand coding scheme (MCS) to each of the contention-based resource zones(task 504). In certain embodiments, task 504 assigns different MCSs tothe contention-based resource zones. In practice, the MCSs can beassigned to support different data rates, quality of service, and thelike. MCS selection for each zone can be performed based on, forexample, expected channel quality of UEs that are near or far from theeNB, or in the middle of the cell (near, mid, far). In this regard, LTEspecification 36.213 V9.2.0 (2010-06), Section 7.1.7 includes a table ofavailable MCS levels.

The eNB will also obtain minimum power headroom values for thecontention-based resource zones (task 506), expressed in appropriateunits such as dBm. In this regard, each contention-based resource zonewill have a respective minimum power headroom value assigned thereto.The minimum power headroom values will be considered by the UE devicesprior to using contention-based uplink access to the eNB. The minimumpower headroom value for a given contention-based resources zone will beinfluenced at least in part by the particular MCS assigned to that zone,because the power requirements for each MCS might vary. Thus, theminimum power headroom values are correlated to the assigned MCSs.Depending upon the system implementation, the current operatingconditions, and/or other factors, the minimum power headroom values maybe different for each of the contention-based resource zones, or atleast two of the minimum power headroom values might be the same.

When system load is low, collision may not be an issue withcontention-based uplink access. However, the load may change from timeto time and the eNB should have the ability to manage collision.Accordingly, a probability factor can be sent to a UE device for usewhen deciding whether it can transmit using a contention-based resource.The probability factor influences whether UE devices in the systemactually perform contention-based uplink transmission. For example,under very light load conditions (where collisions are unlikely), the UEdevices should have a relatively high probability of utilizingcontention-based uplink resources. On the other hand, under high loadconditions (where collisions are more likely), the UE devices shouldhave a lower probability of utilizing contention-based uplink resources.The eNB can manage contention-based uplink access by the UE devices byupdating the probability factor as needed to reflect dynamicallychanging system conditions. The illustrated embodiment of the process500 assumes that the eNB is responsible for calculating (task 508) aprobability factor that influences contention-based uplink access by theUE devices in the manner described above. In practice, the probabilityfactor may be calculated based upon current operating conditions such assystem loading, available resources, the number of UE devices activelysupported by the eNB, and the like. It should be understood however,that calculating a probability factor is optional and not essential tothe method.

The process 500 may continue by preparing and formatting thecontention-based configuration data in an appropriate manner that issuitable for transmission to the UE devices (task 510). In practice, thecontroller of the eNB can perform task 510 to package, format, orotherwise arrange the contention-based configuration data for transportvia one or more signaling channels (e.g., the PDCCH). For example, thecontention-based configuration data can be prepared in a predefinedmessage format with designated fields for the various types ofconfiguration information described above with reference to FIG. 4. Thisenables the eNB to send the contention-based configuration data to theUE devices (task 512) in a format that is recognized and understood bythe UE devices. The eNB could also broadcast or otherwise send thecalculated probability factor to the UE devices (task 514). For example,the probability factor could be transmitted on the physical broadcastchannel (PBCH). Alternatively (or additionally), the probability factorcan be sent dynamically in the PDCCH. In this regard, the probabilityfactor could be included in a field of the contention-basedconfiguration data, along with the fields for the other configurationinformation depicted in FIG. 4.

Some or all of the process 500 can be repeated as often as necessary ordesired. Indeed, the contention-based configuration data and/or theprobability factor could be updated once every subframe, once everyframe, or at any designated interval. Accordingly, FIG. 5 depicts theprocess 500 repeating after task 514. The illustrated embodiment assumesthat tasks 502, 504, and 506 are repeated for each iteration. Inpractice, however, the number, size, and arrangement of thecontention-based resource zones, the MCSs assigned to each zone, and/orthe minimum power headroom value assigned to each zone could be fixedafter their initial determination or calculation. In other embodiments,the number, size, and arrangement of the contention-based resourcezones, the MCSs assigned to each zone, and/or the minimum power headroomvalue assigned to each zone could be updated less frequently than theprobability factor. These and other variations of the process 500 arecontemplated by this disclosure.

The UE devices can use contention-based uplink access to minimizelatency and to transmit occasional packets without incurring highoverload. In this regard, FIG. 6, is a flow chart that illustrates anexemplary operating process 600 performed by a UE device. The process600 begins with the UE device receiving and processing contention-basedconfiguration data, which is sent by the eNB (task 602). In preferredembodiments, the received contention-based configuration data includesat least the information mentioned above with reference to FIG. 4.

If the UE device determines that contention-based uplink access shouldnot be used at this time, then the UE device can perform uplink accessusing a dedicated and scheduled transmission scheme. If, however, the UEdevice decides to use contention-based uplink access, then the process600 continues by obtaining, calculating, or otherwise determining itscurrently available power headroom (task 604). In practice, the UEdevice can perform certain self-monitoring or self-diagnostic proceduresto obtain its currently available power headroom in a real-time orvirtually real-time manner. The currently available power headroom valuecan then be compared to the minimum power headroom values associatedwith the available contention-based resource zones (task 606). Asmentioned above, these minimum power headroom values are received aspart of the contention-based configuration data, as depicted in FIG. 4.Ideally, the currently available power headroom of the UE device willexceed all of the received minimum power headroom values, thus enablingthe UE device to use any of the contention-based resource zones. Inpractice, however, the currently available power headroom may notsatisfy one or more of the received minimum power headroom values.Accordingly, task 606 may identify a subset (which may be a propersubset or the entire set) of the contention-based resource zones forwhich the currently available power headroom of the UE device satisfiesthe respective minimum power headroom values. In other words, task 606identifies certain candidate zones that can be reliably used by the UEdevice.

The UE device may then select one of the zones from the identifiedsubset of contention-based resource zones (task 608). This selection maybe performed randomly, in an ordered fashion, or according to anyspecified rule or algorithm. For example, the selection may favor zonesthat support higher data rates, or it may favor zones having lowerminimum power headroom requirements. The selected zone may be consideredto be the transmit resource zone for this iteration of the process 600.In addition, the process 600 may proceed with one or more optional steps(shown in dashed lines) if so desired. For example, the process 600identifies or obtains the MCS assigned to the selected transmit resourcezone (task 610) and configures the UE device in an appropriate manner tosupport that MCS. Thereafter, the UE device transmits a data packetusing the selected contention-based resource zone and using the MCSassociated with the selected zone (task 612). For this embodiment, thedata is transmitted with the identifier of the UE device (e.g., itsC-RNTI) and a buffer status report if there is additional data in thebuffer of the UE device. This information allows the eNB to determinethe identify of each transmitting UE device and to determine how best tohandle and process the received data.

FIG. 7 is a flow chart that illustrates another exemplary operatingprocess 700 performed by a UE device. The process 700 begins with the UEdevice receiving and processing contention-based configuration data,which is sent by the eNB (task 702). In preferred embodiments, thereceived contention-based configuration data includes at least theinformation mentioned above with reference to FIG. 4.

If the UE device determines that contention-based uplink access shouldnot be used at this time, then the UE device can perform uplink accessusing a dedicated and scheduled transmission scheme. If, however, the UEdevice decides to use contention-based uplink access, then the process700 continues by selecting one of the contention-based resource zonesidentified in the contention-based configuration data (task 704). Thisselection may be performed randomly, in an ordered fashion, or accordingto any specified rule or algorithm. For example, the selection may favorzones that support higher data rates, or it may favor zones having lowerminimum power headroom requirements. The selected zone may be consideredto be the transmit resource zone for this iteration of the process 700.In addition, the process 700 randomly selects one DMRS cyclic shift(task 706) to be used for the uplink transmission. The process 700 alsoidentifies or obtains the MCS assigned to the selected transmit resourcezone (task 708) and configures the UE device in an appropriate manner tosupport that MCS. Thereafter, the UE device transmits a data packetusing the selected contention-based resource zone, using the MCSassociated with the selected zone, and using the randomly selected DMRScyclic shift (task 710). For this embodiment, the data is transmittedwith the identifier of the UE device (e.g., its C-RNTI) and a bufferstatus report if there is additional data in the buffer of the UEdevice. This information allows the eNB to determine the identify ofeach transmitting UE device and to determine how best to handle andprocess the received data.

FIG. 8 is a flow chart that illustrates another exemplary operatingprocess 800 performed by a UE device. The process 800 assumes that theUE device has some data that needs to be sent to the eNB. Accordingly,the process 800 may identify the amount of data to be transmitted fromthe UE device to the eNB (task 802). The identified amount of data canthen be used as a factor in determining whether the UE device willutilize contention-based uplink access or dedicated and scheduled uplinkaccess. For example, the UE device may compare the identified amount ofdata to a data capacity or threshold amount corresponding to a singlephysical resource allocation. If all of the identified amount of datacan be transmitted using only one physical resource allocation (querytask 804), then the process 800 allows contention-based uplink access(task 812) to be considered. In other words, if only one physicalresource allocation is required to accommodate all of the identifiedamount of data, then contention-based access to the eNB might be aviable candidate (whether or not contention-based access is actuallyused might be subject to other factors, as described below). As usedhere, “one” physical resource allocation means the resource allocationconfigured for contention-based access. Thus, if a relatively smallamount of data needs to be transmitted by the UE device, it may bepossible to use contention-based access. For example, ifcontention-based access is configured to support 100 bits, but thepacket size is 400 bits, then four different transmissions would berequired. In such a situation, contention-based access should be avoidedbecause the likelihood that all four transmissions will be successfulwithout collision would be relatively low and it might take anundesirably long amount of time to successfully send and receive all thedata. Instead, one dedicated transmission will accommodate all 400 bitsat once.

If, however, the identified amount of data cannot be transmitted usingonly one physical resource allocation (query task 804), then the process800 determines or identifies the next scheduled transmit time (if any)for dedicated access to the eNB (task 806). It should be realized thattask 806 assumes that the UE device is suitably configured to supportboth contention-based uplink access and traditional dedicated andscheduled uplink access methodologies. In practice, the next scheduledtransmit time may be associated with an SRI. In particular, the nextscheduled transmit time may be dictated by the current SRI period of theUE device. For this particular embodiment, the UE device compares thetime until the next scheduled transmit time (T) to a threshold amount oftime (T_(TH)). If the time until the next scheduled transmit time is notgreater than the designated threshold amount of time (query task 808),then contention-based uplink access is not allowed and the UE deviceperforms uplink access using the dedicated and scheduled transmissionscheme (task 810). In this situation, the UE device may transmit a datapacket containing at least some of the identified amount of data, usingscheduled dedicated access to the eNB. In other words, the UE deviceuses scheduled dedicated uplink access when both: (a) the time until thenext scheduled transmit time is shorter than the threshold amount oftime; and (b) the identified amount of data cannot be transmitted usingonly one resource allocation.

If, however, the time until the next scheduled transmit time is longerthan the designated threshold amount of time (query task 808), then theprocess 800 allows the UE device to consider contention-based uplinkaccess (task 812). Whether or not contention-based access is actuallyused might be subject to other factors, as described below. In practice,the threshold amount of time may be equal to the time associated with afixed number of subframes or frames, if so desired. For example, thethreshold amount of time might correspond to the time normally used forthe transmission of three subframes (e.g., three milliseconds).

If the UE device determines that contention-based uplink access shouldnot be used at this time (query task 814), then the UE device performsuplink access using the dedicated and scheduled transmission scheme(task 816). If, however, the UE device decides to use contention-baseduplink access, then the UE device transmits a data packet using thecontention-based uplink access scheme (task 818). For this embodiment,the data is transmitted with the identifier of the UE device (e.g., itsC-RNTI) and a buffer status report if there is additional data in thebuffer of the UE device. This information allows the eNB to determinethe identify of each transmitting UE device and to determine how best tohandle and process the received data.

A basic UE procedure for transmitting on a contention-based resource ispresented here with reference to FIG. 9, which is a flow chart thatillustrates an exemplary operating process 900 performed by a UE device.The process 900 begins with the UE device receiving and processingcontention-based configuration data, which is sent by the eNB (task902). In preferred embodiments, the received contention-basedconfiguration data includes at least the information mentioned abovewith reference to FIG. 4. The UE device may also receive and process thecurrent probability factor, which may be broadcast or otherwisetransmitted by the eNB (task 904).

The process 900 assumes that the UE device has some data that needs tobe sent to the eNB. Accordingly, the process 900 may identify the amountof data to be transmitted from the UE device to the eNB (task 906). Theidentified amount of data can then be used as a factor in determiningwhether the UE device will utilize contention-based uplink access ordedicated and scheduled uplink access. For example, the UE device maycompare the identified amount of data to a data capacity or thresholdamount corresponding to a single physical resource allocation. If all ofthe identified amount of data can be transmitted using only one physicalresource allocation (query task 908), then the process 900 allowscontention-based uplink access (task 910) to be considered. In otherwords, if only one physical resource allocation can accommodate all ofthe identified amount of data, then contention-based access to the eNBmight be a viable candidate (whether or not contention-based access isactually used might be subject to other factors, as described below). Asused here, “one” physical resource allocation means the resourceallocation configured for contention-based access. Thus, if a relativelysmall amount of data needs to be transmitted by the UE device, it may bepossible to use contention-based access. For example, ifcontention-based access is configured to support 100 bits, but thepacket size is 400 bits, then four different transmissions would berequired. In such a situation, contention-based access should be avoidedbecause the likelihood that all four transmissions will be successfulwithout collision would be relatively low and it might take anundesirably long amount of time to successfully send and receive all thedata. Instead, one dedicated transmission will accommodate all 400 bitsat once.

If, however, the identified amount of data cannot be transmitted usingonly one physical resource allocation (query task 908), then the process900 determines or identifies the next scheduled transmit time (if any)for dedicated access to the eNB (task 912). It should be realized thattask 912 assumes that the UE device is suitably configured to supportboth contention-based uplink access and traditional dedicated andscheduled uplink access methodologies. In practice, the next scheduledtransmit time may be associated with an SRI. In particular, the nextscheduled transmit time may be dictated by the current SRI period of theUE device. For this particular embodiment, the UE device compares thetime until the next scheduled transmit time (T) to a threshold amount oftime (T_(TH)). If the time until the next scheduled transmit time is notgreater than the designated threshold amount of time (query task 914),then contention-based uplink access is not allowed and the UE deviceperforms uplink access using the dedicated and scheduled transmissionscheme (task 916). In this situation, the UE device may transmit a datapacket containing at least some of the identified amount of data, usingscheduled dedicated access to the eNB. In other words, the UE deviceuses scheduled dedicated uplink access when both: (a) the time until thenext scheduled transmit time is shorter than the threshold amount oftime; and (b) the identified amount of data cannot be transmitted usingonly one resource allocation.

If, however, the time until the next scheduled transmit time is longerthan the designated threshold amount of time (query task 914), then theprocess 900 allows the UE device to consider contention-based uplinkaccess (task 918). Whether or not contention-based access is actuallyused might be subject to other factors, as described below. In practice,the threshold amount of time may be equal to the time associated with afixed number of subframes or frames, if so desired. For example, thethreshold amount of time might correspond to the time normally used forthe transmission of three subframes (e.g., three milliseconds).

If the process 900 allows contention-based uplink access to beconsidered (via task 910 or task 918), then the UE device uses thecurrent probability factor to determine whether to access the eNB usingcontention-based resources (task 920). Thus, the probability factorinfluences whether the UE device actually performs contention-baseduplink transmission. Indeed, whether or not the UE device uses thecontention-based uplink access scheme is dictated by the probabilityfactor. As one non-limiting example, the probability factor (p) is anumber such that 0≦p<1. The UE device decides to transmit using acontention-based resource with the probability (1−p). If the UE devicedoes not utilize contention-based uplink access at this time, then itsnext decision (assuming that a new probability factor is not received)will be governed by the probability (1−p²), and so on.

If the UE device determines that contention-based uplink access shouldnot be used at this time (query task 922), then the UE device performsuplink access using the dedicated and scheduled transmission scheme(task 924). If, however, the UE device decides to use contention-baseduplink access, then the process 900 continues by obtaining, calculating,or otherwise determining its currently available power headroom (task926). In practice, the UE device can perform certain self-monitoring orself-diagnostic procedures to obtain its currently available powerheadroom in a real-time or virtually real-time manner. The currentlyavailable power headroom value can then be compared to the minimum powerheadroom values associated with the available contention-based resourcezones (task 928). As mentioned above, these minimum power headroomvalues are received as part of the contention-based configuration data,as depicted in FIG. 4. Ideally, the currently available power headroomof the UE device will exceed all of the received minimum power headroomvalues, thus enabling the UE device to use any of the contention-basedresource zones. In practice, however, the currently available powerheadroom may not satisfy one or more of the received minimum powerheadroom values. Accordingly, task 928 may identify a subset (which maybe a proper subset or the entire set) of the contention-based resourcezones for which the currently available power headroom of the UE devicesatisfies the respective minimum power headroom values. In other words,task 928 identifies certain candidate zones that can be reliably used bythe UE device.

The UE device may then select one of the zones from the identifiedsubset of contention-based resource zones (task 930). This selection maybe performed randomly, in an ordered fashion, or according to anyspecified rule or algorithm. For example, the selection may favor zonesthat support higher data rates, or it may favor zones having lowerminimum power headroom requirements. The selected zone may be consideredto be the transmit resource zone for this iteration of the process 900.In addition, the process 900 randomly selects one DMRS cyclic shift(task 932) to be used for the uplink transmission. The process 900 alsoidentifies or obtains the MCS assigned to the selected transmit resourcezone (task 934) and configures the UE device in an appropriate manner tosupport that MCS. Thereafter, the UE device transmits a data packetusing the selected contention-based resource zone, using the MCSassociated with the selected zone, and using the randomly selected DMRScyclic shift (task 936). For this embodiment, the data is transmittedwith the identifier of the UE device (e.g., its C-RNTI) and a bufferstatus report if there is additional data in the buffer of the UEdevice. This information allows the eNB to determine the identity ofeach transmitting UE device and to determine how best to handle andprocess the received data.

With the procedure described above, a UE device uses a contention-basedzone if the expected latency of waiting for contention-free access iscomparatively higher, or if the efficiency of using contention-basedaccess is greater. If the amount of data to be transmitted is relativelylow, (e.g. in machine-type communication), the UE devices need not beallocated uplink control signaling such as Channel Quality Information(CQI) and SRI, and may instead be instructed to use contention-basedaccess. In this regard, CQI/SRI set-up is part of dedicated uplinkcontrol signaling, which consumes uplink resources. Accordingly, thisapproach can reduce uplink overhead.

In addition, additional restrictions can be placed on contention-basedaccess if so desired. For example, restrictions based on traffic typescan be defined. Thus, guaranteed bit rate (GBR) flows with packet delaybudget less than a defined amount (T_(d)) could have sub-priority amongcertain classes (e.g., gaming has higher priority thanconversational-video). On the other hand, non-GBR flows would be allowedaccess but no further buffer status reports will be served (e.g., TCPACK/NACK only). Restrictions can also be placed based on trafficactivities. For instance, contention-based access is not allowed if theUE device has sent SRI and is still waiting for an uplink grant, or ifthe UE device has received an uplink grant, or if the UE device hasalready sent data to the eNB with a buffer status report. In this case,the UE device already has been or will soon be assigned dedicatedresources, so contention-based access is not likely to reduce latency.

The system 100 described here also considers how the eNB will processdata received via contention-based resources. In this regard, FIG. 10 isa flow chart that illustrates another exemplary operating process 1000performed by a base station, and FIG. 11 is a diagram that illustratestiming associated with the uplink transmission of a data packet and thedownlink transmission of a corresponding acknowledgement message. Thenumbered squares in FIG. 11 represent data packets, time slots, timeblocks, or any predefined period associated with the operation of theeNB and the UE, with time increasing to the right.

Referring to FIG. 10, the process 1000 begins with the eNB receiving adata packet from a UE device (task 1002) via contention-based uplinkaccess. For this particular embodiment, the received data packetincludes an identifier that uniquely identifies the transmitting UEdevice within the domain of the system. The identifier may be, forexample, a C-RNTI. The eNB decodes (or attempts to decode) the receiveddata packet (task 1002). The eNB may also perform one or more tests orchecks to determine whether or not the data was decoded correctly. Forexample, the eNB could perform a cyclic redundancy check (CRC) on thedecoded data. If the received data packet was not correctly decoded(query task 1006), then the eNB does not transmit an acknowledgmentmessage to the UE device within the designated response window (task1008). Consequently, if the UE device does not receive anacknowledgement message within the designated response window, then itwill assume that the eNB either did not receive the data packet or didnot correctly decode the data packet. Accordingly, the UE device canthen either transmit the data packet again using contention-based accessor it can wait for the next SRI slot to send a scheduling request to theeNB.

Certain exemplary embodiments of the system 100 use uplink grantmessages as acknowledgement messages. Therefore, if the UE device doesnot receive an uplink grant within the designated response window, thenit assumes that the eNB did not correctly decode the data packet. Theuse of uplink grant messages in this manner is desirable because theformat and use of uplink grants are already defined in the LTEspecification. Accordingly, if the received data packet is not correctlydecoded, then the eNB will not send an uplink grant back to the UEdevice (task 1008). It should be appreciated that an uplink grantrepresents control information sent on the PDCCH that providesinformation about how the UE device will access the system in theuplink. For dedicated access, an uplink grant is addressed to a UEdevice (using, for example, the C-RNTI). For contention-based access, anuplink grant will address a special RNTI that is common to all UEdevices (i.e., all UE devices will try to read this grant). Informationfields/contents for an uplink grant are defined in 3GPP specification36.212 V9.2.0 (2010-06), Section 5.3.3.1.1. They include, for instance,MCS, hopping field, DMRS, and power control information. The UE deviceknows whether the grant is successfully received if it successfullydecodes the information (CRC check of message is good).

If the received data packet is correctly decoded, then the eNB may alsoreceive a buffer status report from the UE device; the buffer statusreport could be received with the data packet (task 1010). The bufferstatus report indicates an amount of data remaining to be transmitted bythe UE device. Note that the buffer status report could indicate that noadditional data remains to be transmitted. In FIG. 11, the arrow 1102represents the contention-based uplink transmission of the data packet,the C-RNTI, and the buffer status report from the UE device to the eNB.Upon receipt of this information, the eNB can perform the necessaryprocessing, decoding, analysis, and handling during a processing timeperiod. In FIG. 11, the arrow 1104 represents this processing timeperiod. It should be appreciated that the actual processing time period1104 could span any number of time “blocks,” and that FIG. 11 is merelyexemplary.

Referring back to FIG. 10, the eNB analyzes the received buffer statusreport to determine the amount of data remaining to be transmitted bythe UE device (task 1012) and the process 1000 checks whether more dataremains to be transmitted by the UE device (query task 1014). Asdescribed above, the eNB can consult the buffer status report todetermine whether more data remains to be transmitted. When more dataremains to be transmitted by the UE device, the eNB prepares an uplinkgrant that includes or otherwise indicates the C-RNTI of thetransmitting UE device (task 1016). Notably, this uplink grant isprepared in accordance with the LTE specification because it actuallyserves as a true uplink grant that enables the UE device to transmit itsremaining data using the traditional dedicated and scheduled resourceapproach. This uplink grant is transmitted to the originating UE devicewithin the designated response window, via a signaling channel such asthe PDCCH (task 1018). It should be appreciated that this uplink grantserves at least two purposes: (1) as an acknowledgement message; and (2)as a grant that enables the UE device to transmit its remaining datausing dedicated and scheduled resources. The inclusion of the C-RNTI inthis uplink grant enables the UE device to confirm that the uplink grantrepresents an acknowledgement message for its recently transmitted datapacket.

Referring again to FIG. 11, the response window 1106 for this example istwo time blocks (from the perspective of the eNB). Of course, theresponse window 1106 could be defined to be any number of time blockscorresponding to any number of packets, time slots, etc. As shown inFIG. 11, the acknowledgement message 1108 (e.g., the uplink grant) issent before the response window 1106 lapses.

If query task 1014 determines that no additional data remains to betransmitted by the UE device, then the process 1000 prepares a dummyuplink grant that includes or otherwise indicates the C-RNTI of thetransmitting UE device (task 1020). As used here, a “dummy” uplink grantis one that serves only as an acknowledgement message. In other words, adummy uplink grant does not function as a true grant as defined by theLTE specification. Consequently, a dummy uplink grant will convey lesscontextual information than an actual uplink grant, although it willhave the same size, format, and fields as defined in a “normal” uplinkgrant, however, some of the fields will be set to an invalid or reservedstate so that the UE device will detect the message as a dummy uplinkgrant rather than a normal uplink grant. Therefore, the content of theacknowledgement message (i.e., the uplink grant) is influenced by theamount of data remaining to be transmitted by the UE device. The dummyuplink grant is transmitted to the originating UE device within thedesignated response window, via a signaling channel such as the PDCCH(task 1022). Again, the inclusion of the C-RNTI in this dummy uplinkgrant enables the UE device to confirm that the dummy uplink grantrepresents an acknowledgement message for its recently transmitted datapacket.

Notably, an uplink grant (whether an actual grant or a dummy grant)serves as an implicit ACK to let the UE device know that the eNB hassuccessfully received and decoded the data packet. If the UE device hasmore data to transmit, the grant will be an actual uplink grant, and anadditional uplink resource will be allocated to the UE device in aconventional manner. If the UE device does not receive an uplink grant(actual or dummy) within the predefined response window, then the UEdevice will proceed as if it had received a NACK. Using this approach,contention resolution is managed using uplink grants (actual grants anddummy grants). Alternately, an ACK format can be created fortransmission using the PDCCH, where the eNB echoes back all C-RNTIsconveyed with data packets that were correctly decoded.

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or embodiments described herein are not intended tolimit the scope, applicability, or configuration of the claimed subjectmatter in any way. Rather, the foregoing detailed description willprovide those skilled in the art with a convenient road map forimplementing the described embodiment or embodiments. It should beunderstood that various changes can be made in the function andarrangement of elements without departing from the scope defined by theclaims, which includes known equivalents and foreseeable equivalents atthe time of filing this patent application.

What is claimed is:
 1. A method of operating a base station in awireless communication system, the method comprising: determining aplurality of contention-based resource zones for a shared channel of thebase station, each of the contention-based resource zones comprising arespective number of physical resource blocks; assigning a respectivemodulation and coding scheme to each of the contention-based resourcezones, resulting in assigned modulation and coding schemes; obtaining,for each of the contention-based resource zones, a respective minimumpower headroom value to be considered by user equipment devices in thewireless communication system, resulting in obtained minimum powerheadroom values; and sending contention-based configuration data to userequipment devices in the wireless communication system, thecontention-based configuration data comprising zone data that identifiesthe plurality of contention-based resource zones, modulation and codingscheme data that identifies the assigned modulation and coding schemes,and minimum power headroom data that identifies the obtained minimumpower headroom values.
 2. The method of claim 1, wherein the obtainedminimum power headroom values are different for each of thecontention-based resource zones.
 3. The method of claim 1, wherein atleast two of the obtained minimum power headroom values are the same. 4.The method of claim 1, wherein the sending step sends thecontention-based configuration data in a signaling channel.
 5. Themethod of claim 4, wherein the sending step sends the contention-basedconfiguration data using Radio Resource Control (RRC) signaling.
 6. Themethod of claim 4, wherein the sending step sends the contention-basedconfiguration data using a physical downlink control channel (PDCCH). 7.The method of claim 1, further comprising: calculating a probabilityfactor that influences whether user equipment devices in the wirelesscommunication system perform contention-based uplink transmission; andbroadcasting the probability factor to user equipment devices in thewireless communication system.
 8. A base station for operation in awireless communication system, the base station comprising: a wirelesscommunication module that supports a shared channel for user equipmentdevices in the wireless communication system, and that supports asignaling channel between the base station and the user equipmentdevices; and a controller operatively associated with the wirelesscommunication module and configured to prepare contention-basedconfiguration data for the user equipment devices; wherein the wirelesscommunication module sends the contention-based configuration data tothe user equipment devices using the signaling channel; thecontention-based configuration data comprises: zone data that identifiesa plurality of contention-based resource zones for the shared channel,each of the contention-based resource zones comprising a respectivenumber of physical resource blocks; modulation and coding scheme datathat identifies modulation and coding schemes assigned to thecontention-based resource zones; and minimum power headroom data thatidentifies minimum power headroom values assigned to thecontention-based resource zones; and contention-based uplinktransmissions by the user equipment devices are influenced by theminimum power headroom values.
 9. The base station of claim 8, whereinthe modulation and coding scheme data identifies a different modulationand coding scheme for each of the contention-based resource zones. 10.The base station of claim 8, wherein the minimum power headroom dataidentifies a different minimum power headroom value for each of thecontention-based resource zones.
 11. The base station of claim 8,wherein at least two of the minimum power headroom values are the same.12. The base station of claim 8, wherein the wireless communicationmodule sends the contention-based configuration data using RadioResource Control (RRC) signaling.
 13. The base station of claim 8,wherein the wireless communication module sends the contention-basedconfiguration data using a physical downlink control channel (PDCCH).14. The base station of claim 8, wherein the contention-basedconfiguration data comprises a probability factor that influenceswhether the user equipment devices perform contention-based uplinktransmission.